cpus: Register VMState per user / system emulation

Simplify cpu-target.c by extracting mixed vmstate code
into the cpu_vmstate_register() / cpu_vmstate_unregister()
helpers, implemented in cpu-user.c and cpu-system.c.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250123234415.59850-20-philmd@linaro.org>

hw/core/cpu-system.c

@@ -21,11 +21,15 @@
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "exec/address-spaces.h"
+#include "exec/cputlb.h"
 #include "exec/memory.h"
+#include "exec/tb-flush.h"
 #include "exec/tswap.h"
 #include "hw/qdev-core.h"
 #include "hw/qdev-properties.h"
 #include "hw/core/sysemu-cpu-ops.h"
+#include "migration/vmstate.h"
+#include "system/tcg.h"
 
 bool cpu_paging_enabled(const CPUState *cpu)
 {
@@ -194,3 +198,114 @@ void cpu_exec_initfn(CPUState *cpu)
     cpu->memory = get_system_memory();
     object_ref(OBJECT(cpu->memory));
 }
+
+static int cpu_common_post_load(void *opaque, int version_id)
+{
+    if (tcg_enabled()) {
+        CPUState *cpu = opaque;
+
+        /*
+         * 0x01 was CPU_INTERRUPT_EXIT. This line can be removed when the
+         * version_id is increased.
+         */
+        cpu->interrupt_request &= ~0x01;
+
+        tlb_flush(cpu);
+
+        /*
+         * loadvm has just updated the content of RAM, bypassing the
+         * usual mechanisms that ensure we flush TBs for writes to
+         * memory we've translated code from. So we must flush all TBs,
+         * which will now be stale.
+         */
+        tb_flush(cpu);
+    }
+
+    return 0;
+}
+
+static int cpu_common_pre_load(void *opaque)
+{
+    CPUState *cpu = opaque;
+
+    cpu->exception_index = -1;
+
+    return 0;
+}
+
+static bool cpu_common_exception_index_needed(void *opaque)
+{
+    CPUState *cpu = opaque;
+
+    return tcg_enabled() && cpu->exception_index != -1;
+}
+
+static const VMStateDescription vmstate_cpu_common_exception_index = {
+    .name = "cpu_common/exception_index",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = cpu_common_exception_index_needed,
+    .fields = (const VMStateField[]) {
+        VMSTATE_INT32(exception_index, CPUState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static bool cpu_common_crash_occurred_needed(void *opaque)
+{
+    CPUState *cpu = opaque;
+
+    return cpu->crash_occurred;
+}
+
+static const VMStateDescription vmstate_cpu_common_crash_occurred = {
+    .name = "cpu_common/crash_occurred",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = cpu_common_crash_occurred_needed,
+    .fields = (const VMStateField[]) {
+        VMSTATE_BOOL(crash_occurred, CPUState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+const VMStateDescription vmstate_cpu_common = {
+    .name = "cpu_common",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .pre_load = cpu_common_pre_load,
+    .post_load = cpu_common_post_load,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT32(halted, CPUState),
+        VMSTATE_UINT32(interrupt_request, CPUState),
+        VMSTATE_END_OF_LIST()
+    },
+    .subsections = (const VMStateDescription * const []) {
+        &vmstate_cpu_common_exception_index,
+        &vmstate_cpu_common_crash_occurred,
+        NULL
+    }
+};
+
+void cpu_vmstate_register(CPUState *cpu)
+{
+    if (qdev_get_vmsd(DEVICE(cpu)) == NULL) {
+        vmstate_register(NULL, cpu->cpu_index, &vmstate_cpu_common, cpu);
+    }
+    if (cpu->cc->sysemu_ops->legacy_vmsd != NULL) {
+        vmstate_register(NULL, cpu->cpu_index,
+                         cpu->cc->sysemu_ops->legacy_vmsd, cpu);
+    }
+}
+
+void cpu_vmstate_unregister(CPUState *cpu)
+{
+    CPUClass *cc = CPU_GET_CLASS(cpu);
+
+    if (cc->sysemu_ops->legacy_vmsd != NULL) {
+        vmstate_unregister(NULL, cc->sysemu_ops->legacy_vmsd, cpu);
+    }
+    if (qdev_get_vmsd(DEVICE(cpu)) == NULL) {
+        vmstate_unregister(NULL, &vmstate_cpu_common, cpu);
+    }
+}

hw/core/cpu-user.c

@@ -10,6 +10,7 @@
 #include "hw/qdev-core.h"
 #include "hw/qdev-properties.h"
 #include "hw/core/cpu.h"
+#include "migration/vmstate.h"
 
 static const Property cpu_user_props[] = {
     /*
@@ -30,3 +31,14 @@ void cpu_exec_initfn(CPUState *cpu)
 {
     /* nothing to do */
 }
+
+void cpu_vmstate_register(CPUState *cpu)
+{
+    assert(qdev_get_vmsd(DEVICE(cpu)) == NULL ||
+           qdev_get_vmsd(DEVICE(cpu))->unmigratable);
+}
+
+void cpu_vmstate_unregister(CPUState *cpu)
+{
+    /* nothing to do */
+}